Paper drying machine



Feb. 19, 1963 w. A. DICKENS PAPER DRYING MACHINE 6 Sheets-Sheet 1 FiledD60. 21, 1959 Feb. 19, 1963 w. A. DICKENS PAPER DRYING MACHINE FiledDec. 21, 1959 6 Sheets$heet 2 Feb. 19, 1963 w. A. DICKENS PAPER DRYINGMACHINE 6 Sheets-Sheet 3 Filed Dec. 21, 1959\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\&\\\\\\\\\\\\\\\\\ Feb.19, 1963 w. A. DICKENS PAPER DRYING MACHINE s Sheets-Sheet 4 Filed Dec.21, 1959 W! NEW NIH 1963 w. A. DICKENS 3,077,675

PAPER DRYING MACHINE Fiied Dec. 21, 1959 6 Sheets-Sheet 5 Feb. 19, 1963w. A. DICKENS 3,077,675

PAPER DRYING MACHINE Filed Dec. 21, 1959 e Sheets-Sheet s United StatesPatent ()fiice 7 3,077,675 Patented Feb. 19, 1963 3,077,675 PAPER DRYINGMACHINE William A. Dickens, Neenah, Wis, assignor to Kimberly- (IiarkCorporation, Neenah, Wis, a corporation of Delaware Filed Dec. 21, 1959,Ser. No. 860,914 2 Claims. (Ci. 34-122) This invention relates topapermaking machines and more particularly to rolls of such machineswhich have air applied to them for either cooling or heating the rolls.Such a roll may be the large cylinder or Yankee drier drum of a papermachine on which the moist paper is pressed for drying and glazing.

Air is conventionally applied to paper web on a Yankee drier drum bymeans of a hood located over the drier drum. A plurality of rows ofround cross section pipes may be arranged around the periphery of thedrum which may vary from 8 to 12 feet in diameter. The pipes are eachprovided with a series of nozzles directing air from the interior of thepipe on to the periphery of the drum, and the pipes are spaced apartjust sufliciently to allow for the expended air to find its way betweenadjacent nozzles and pipes.

A more uniform application of air to the drum may be obtained using aplurality of ducts or plenum chambers within the hood disposed about thedrier drum and extending parallel to the axis of the drum. Each of theseducts has a plurality of apertures or nozzles extending through the wallof the duct facing the surface of the drum, and the apertures or nozzlesare arranged in a pattern so that air is substantially uniformly appliedon the surface of the drum beneath the duct.

The ducts are generally between 4 to 20 inches wide and have about 2 or3 inches spacing between them. The spacing is provided so that anywedding or paper accumulating on the drier drum or on the surfaces ofthe ducts facing the drier drum may be removed by drawing the wadding orpaper through the spaces between the ducts.

The provision of such spacing between the ducts, however, has caused theapplication of air to the surface of the drum to be non-uniformthroughout the part of the drum subtended by the ducts due to the factthat there has been no provision for directing air from any of the ductson to the surfaces of the drum opposite the spaces between the ducts.

It is an object of the present invention to provide an improvedapparatus for directing air on to a drum substantially uniformlythroughout the part of the drum subtended by the air applicationapparatus. In particular, it is an object of the invention to providediagonally extending apertures or diagonally extending nozzles adjacentthe edges of the ducts above mentioned for directing air on the surfacesof the drum opposite the spaces between the ducts for achieving thisuniformity of air application.

' The invention consists of the novel constructions, arrangements anddevices to be hereinafter described and claimed for carrying out theabove stated objects and such other objects as will be apparent from thefollowing description of preferred forms of the invention, illustratedwith reference to the accompanying drawings wherein:

FIG. 1 is a side view of a Yankee drier with which a drier hoodutilizing the principles of the invention may be utilized;

FIG. 2 is a transverse sectional view of the hood;

FIG. 3 is a longitudinal sectional view of the hood;

FIG. 4 is a fragmentary view similar to FIG. 3, on an enlarged scale,showing a plurality of plenum chambers in the hood;

FIG. 5 is a fragmentary sectional view similar to FIG. 4 on a stillfurther enlarged scale;

FIG. 6 is a sectional view of a nozzle with which the plenum chambersare each equipped;

FIG. 7 is a plan view of a plenum chamber showing the spacing anddistribution of the nozzles in the plenum chamber;

FIG. 8 is a schematic elevational view of a drier hood with a pluralityof plenum chambers of modified form;

FIG. 9 is a plan view of the modified plenum chambers showing thespacing and distribution of nozzles therein;

FIG. 10 is a fragmentary view of a face of a plenum chamber providedwith orifices in lieu of nozzles;

FIG. 11 is a perspective view of a breaker stack provided with a coolingsystem embodying the principles of the invention;

FIG. 12 is a transverse sectional view of the breaker stack; and

FIG. 13 is a schematic showing of an orifice and the flow of fluidtherethrough.

Like characters of reference designate like parts in the several views.

Referring now to the drawings and particularly to FIG. 1 thereof, theillustrated machine comprises the usual drum or cylinder 10 mounted forrotation on the frame 11 and provided with the usual pressure roll 12.The paper web to be dried by the roll 10 is carried by a felt Web 13which travels around felt rolls 14. The roll 12 is rotatably mounted inbrackets 15 each attached to an arm 16. Each arm 16 is pivoted at 17 tothe frame 11, and the pressure roll 12 is forced against the surface ofthe drum 10 by a ram 18 which bears against each arm 16.

The dried paper web is removed from the surface of the drum it by acreping doctor which includes a doctor blade 19 movably secured within ablade holder 20. The ends of the holder are provided with shafts 21which are rotatably mounted within guide blocks 22. The blocks 22 inturn are each slidably mounted within a slide assembly 23 attached topivot frame 24 pivotally carried by frame 11. Through the slidearrangement provided by the slide blocks 22 and slide assembly 23, thevertical position of the doctor blade I? can be varied, as desired, toobtain the best creping angle.

The doctor blade holder 20 and the blade 19 are pivoted by a togglemechanism 25 which is attached through a lever arm 26 to one of theshafts 21. In addition, a spring loading mechanism 27 is connectedthrough the toggle mechanism 25 to provide a resilient contact for thedoctor blade against the surface of the drum 10.

A hood 28 is disposed about the drum 10 (see FIGS. 2 and 3). A pair ofsemi-annular headers 29 and 30 are provided within the hood 28 and aremounted on the frame 111, being positioned adjacent opposite sides ofthe drum It). The headers 29 and 30 are connected respectively by supplyducts 31 and 32 to the outlet 33 of an air fan or blower 34 which is oflarge capacity and may be supported on a platform provided on the frame11 or elsewhere. Each header 29 and 30 extends around at least /2 of thedrum 1t) and diminishes progressively in cross section away from thefan.

A plurality of ducts or plenum chambers 35 each having sides 36 and 37and an inner wall 38 extends between the headers 29 and 30 (see FIGS. 2,4 and 5). These ducts 35 extend parallel with the longitudinal axis ofthe drum 10 and are equally spaced apart. The ducts in an actualembodiment may, for example, be 5 or 6 inches wide and have spaces ofabout 2 inches between them. The actual drier drum in such a case may beexpected, for

example, to have a radius of about 5 feet.

which are equally spaced from each other lengthwise of the duct asillustrated in FIG. 7. In a particular embodiment of the invention, eachof the nozzles were spaced 012; inch from the nearest nozzle lengthwiseof the duct, and the nozzles were spaced 1-.'2 inch from each othercrosswise of the duct, with the exception of the nozzles 39c and 39Adjacent nozzles-39a are then spaced about 1.6 inch apart, and the samespacing exists for adjacent nozzles 3%, 39d, 39'e, 39gand-39h;

All of the nozzles extend perpendicularly through the wall 38. Thenozzles-39c and- 39f are respectively carried by andextend through edgeportions 38a and 38b of. the wall 38-which extend at anangle A withrespect to the mainportion of the wall 38 (see FIG. 5). The 1102- zles39c and 39 are thus located adjacent the sides of each" of the ducts 35and extend diagonally with respect to the other nozzles 39 so as todischarge air into,the adjacent space between two-ofthe ducts 35.

Each of the nozzles 39 comprises a tubular portion; 40; (see FIG. 6.)which extends-through the wall 38 and which terminates substantially atthe surface. of thewall adja cent the surfaceiofthe drum, Thenozzlescomprise also an outwardly flared portion 41 located within the duct 35-Itwill benotedthat the hood 28 encloses; all of the ducts. 35 and thatportion of the? drumover which the ducts.v 35 lie. The hood is. spacedapart from the drum-surface and'ducts 35 to,- provide, collecting space42 for exhaust or spent air blown against the paper W- from the ducts 35and which passes outwardly to the space 42 between the ducts 35. Anexhaust duct 43 is provided in the hood 28- and incommunication withthespace 42. The hood.28'has a'recirculating air duct 44 connected toand communicatingwith the space 42; The duct. 44 is. connecteddirectlyto-make up air duct 45 that supplies. the fan 34, so that theairsupplied to the ducts.-

through theiheater 46 wherein itis thoroughly heated and is blown fromthe fan 34through outlet 33 into ducts-31 and 32, passingtherefrom'through; headers Hand 30 which distributeittotheducts 35. Theheated air then flows through the nozzles 39 on to the adjacent surfaceof the drier drum 10. The nozzles 39a,39b, 39d, 3 9e, 39g and 3%extending perpendicularly through the center partofeach duct wall 38,which is placedto be perpendicular at its center to'a radial linepassing through the center: of the drum 10,,direct air normally on thesurface of the drum 10; and the nozzlesv39c and 39); extendingsidewardly with respect to the'center part of the wall; 38, direct airon to the-outersurface-of the drum 10:: opposite thespaces. between theducts 35, so as-to-blanket thexsurface of the drum 10 with heatedairsubstantiallyuni formly from one end of the hood 28-tothe other,from. its entrance end-to itsexitendfor the web W.

It will bev noted from FIG: 5 that the center lines of the, nozzles 39a,3%, 39d, 3%, 39g and 39h intersect thesurface of the drier drum 10substantia1ly1.2 inches. apart. The center lines of nozzles-39f, and 390of adjacent ducts 35 intersect the-surfaceof'the drum ltlsubstana tiallyat the same distance from each other and from the centerlinesof adjacentnozzles 39a and 3%,- so that the application of air is substantiallyuniform. not only be-. neath the ducts 35 but also opposite the spacesbetween the ducts. In theparticular embodiment illustrated, the ducts35' have a-width of"7 /2 inches, and there is approximately 2 inchesbetween ducts. The side parts 38a and 38b of the'walls carrying thenozzles 39 and 390 extend 4 at an angle ,A with respect to themainpartsof the walls 38 so as to achieve this uniform air distribution.

For best results and most uniform application of air to the surface ofthe drum 1% from the nozz.es 39, the spac ing of nozzles 39 shallpreferably be /8 inch to 2 inches from neighboring nozzles, bothperipherally and longitudinally of the drum, and the nozzles shallpreferably terminate A2 inch to 2 inches from the surface ofthe drum 10.In addition, the percentagefree area for flow times the nozzlecoefficient of discharge shall preferably be in the range from 1.3 to2.7 percent. The free area for flow is thetotal area of all of thenozzles at their outlet ends divided by the total surface area of thesheet W to which air application is made from the nozzles. The nozzlecoefiicient corresponds. to an orifice coetficient which maybe'explained with reference to.FIG. 13. The; orifice coefiicient,referring to FIG. 13 which showsthe flowof fluid through asimpleorific'e 47, is A over A where A isthe diameter of the; orificeand A is the smallest diameter of the fluid; stream proceeding from theorifice; Analogously for anozzle, with no fluid friction for-agivenpressure-drop,ithe fiowwvould'be F v while,

with the friction'thatac-tually exists, the flow isJF Thenozzleco'efiicient of. discharge wouldthen be Fgover F The coefficient ofdischarge can be easily ascertained by those skilled: in theart for:orifices: andnozzles ofany,

shape using well known chemical engineering principles, such assetforthinzPrinciples of Chemical Engineering, Chapter 3, by-Walker, Lewis,McAdams and Silliland, published by McGraw-Hill BookCo, New York, N.Y.',1937. With an ordinary simple orifice, its coefiicient may be onitheorder of'% while with a properly designed nozzle, the correspondingnozzlecoefficient maybe .94, indicatingv a=substantial difference.Although the nozzles 39 are illustrated asdirecting the air on to thesurface of the drum 10, it will be understood that simple orifices mayinstead: be used; however, due to the different flow behaviorofitheorifices as compared to nozzles, the diametersof the orifices mustbelarger-than the inside diameters of the nozzles to provide the sameairflow, The same spacing of the orifices with respect to each other andto the drumsurfacean'd the same product of-thefree area for flow by thecoeflicient of discharge are preferably used for the orifices as for thenozzles.

The air that'flows' off the surface of the drum 10 returns to the fan34, or as exhausted out of the system, flowingin thespaces between theducts 35'. For the purpose of simply returning the air that isdischarged through the nozzles 39 subsequent to impingement on the outersurface of the drum 10', the spacing between the ducts 35 could becloser. However, at times, the wedding or paper, due to some defect,accumulates on the surface of the waddingor paper can be withdrawn fromthe surface of the drum between the ducts 35, The exhaust air in thehood space 42 exhausts-in part through the duct 43, and

the remaining part is drawn by the recirculation duct 44 for mixturewith make up air in the duct 45in advance of' the heater- 46. Theprovision of this recirculating arrangement for exhaust, air providesthe required amount of air for the ducts 35- with an appropriatecapacity fan, about 10 percent to 40 percent of the air circulated beingfresh or make up air and the balance being exhaust air.

In lieu of the arrangement of nozzles illustrated in FIG. 7, orificesmay instead by utilized as previously mentioned. Also, other-patterns ofnozzles or orifices may be used in lieu of that illustrated in FIG; 7 touniformly apply air to the surface of the drum 10. Referring to FIG. 10,orifices 47a disposed on triangular centers may be used as shown. Theorifices may have a diameter of inchand maybe-located on corners ofequilateral triangles having 1 inch sides. Nozzles may be utilizedinstead of the simple orifices in this arrangement, but as previouslyindicated, the nozzles if properly designed for minimum frictional losswill have a smaller diameter than the orifices for the same total airfiow.

Substantially uniform application of air to the surface of the drum It}may be achieved also without the diagonally extending nozzles 39c and39f or corresponding diagonally extending orifices. This may beaccomplished by locating the ducts 35 closer together such as is shownin FIGS. 8 and 9. in this particular embodiment, the ducts are 3.5inches wide and have a spacing of 0.6 inch between them. As will beobserved from FIG. 9 which shows the arrangement of nozzles in the walls38 of these ducts, the nozzles 39 are provided in patterns of four whichincludes nozzles 13%, 3%, 39m and 3911. The nozzles 39j and 3912 arelocated substantially as close to the side duct walls 36 and 37 aspossible, and the nozzles are disposed on diagonal lines or linesdisposed helically about the drum extending in such a direction that thefour nozzles in one duct 35 will align with four nozzles in an adjacentduct. The nozzles are equally spaced on these diagonally extendinglines, and adjacent nozzles in adjacent ducts 35 will be spacedapproximately the same distance as the nozzles in any of the ducts onthese diagonal lines. The nozzles 39 are disposed on longitudinallyextending lines and this is true of the other nozzles as well. Thelongitudinal lines in the illustrated embodiment are 1.1 inch apart, andthe nozzles along each of these longitudinal lines are located 1.25 inchapart which assures an even distribution of air from each duct. Due tothe close spacing between the ducts 35 and the location of the nozzles39 and 3911 as close as possible to the side walls 37, this uniformityof air application exists also between the ducts 35. This spacing ofducts and nozzles is particularly useful in connection with stronger andheavier papers that do not tend to bunch up and accumulate on thesurface of the roll 16' necessitating the frequent removal of paper fromthe roll surface.

The same uniformity of air application may also be had, using the airfor cooling instead of heating. This may be in connection with a breakerstack conventionally located behind the drier in a paper machine, suchas behind a Yankee drier drum 1% Referring to FIGS. 11 and 12, such abreaker stack may comprise a large bottom roll 48 and upper rolls 49 and50 supported by a frame 51. The paper web W may pass through the nips ofthe rolls 48, 49 and 50 as shown in FIG. 12. Due to lack in uniformityin the rolls of the breaker stack or due to lack of uniformity inthickness of the paper web W, for example, one or more of the rolls 4?),49 and 50 may become non-uniformly heated on its surface. Suchnonuniform heat distribution on the surface of a roll tends to cause theroll to be undesirably non-uniform in diameter. Therefore, it may bedesirable to cool certain sectors of the roll without cooling othersectors so as to bring the roll surface to a uniform temperature acrossthe length of the roll or, more generally, to change the existingtemperature profile, giving it a desired different temperature profile.A hood 52 having a plurality of semicircular plenum chambers 53, witharcuate walls 54 in close proximity to the roll 4%, may be provided forthe roll 48, for example. The walls 54 are provided with the orifices l?or with the nozzles 39, which are arranged with respect to each other inthe same manner as previously described. An air inlet pipe 55 isprovided for each of the chambers 53. The same space between the wall 54and the surface of the roll 4% is preferably provided as between thewalls 33 and the surface of the drum 10; the same hole or nozzle spacingof inch to 2 inches is desirable; and the same percent free area forflow times nozzle or orifice coefficient of 1.3 to 2.7 percent ispreferably used, so that the sa-rne uniformity of air application isachieved for uniformly and effectively cooling the sector of the rollopposite the plenum chamber 53 to which the cooling air is supplied.

The utilization of the orifice or nozzle spacing of inch to 2 inches,the use of the range of 1.3 to 2.7 percent free area for flow timesnozzle or orifice coeificient, and the location of the surface in whichthe orifices or nozzles are disposed between A; inch and 2 inches of thesurface of the roll assures not only uniform air application butprovides a desirably high volume of air flow and heat transfer to thesurface of the roll, as well as a maximum mass transfer, which in thecase of the Yankee drier roll is a maximum drying effect.

It will be observed that both the heating and cooling embodiments of theinvention provide generally arcuate surfaces extending around the rolls.In the FIG. 4 embodiment, the generally arcuate surface is provided bythe plane walls 38 together with the diagonally extending end zones 38aand 38b of the plenum chambers 35. The generally arcuate surface in theFIG. 8 embodiment is provided by the walls 38 between the side walls 36and 37 which are located closely together for adjacent plenum chambers.The generally arcuate surfaces are at an approximately uniform distancefrom the external surfaces of the rolls, and the orifices or nozzlesextend perpendicularly through the walls in which they are disposed andare so spaced in patterns that the air jets impinging on the rolls arespaced substantially uniformly arcuately of the rolls from substantiallyone end of the hood to the other and are also uniformly spacedlongitudinally of the rolls.

Due to the fact that there is a uniform application of air for thecomplete surface of the rolls beneath the drier hood, the drying effectachieved is greater than that achieved by conventional air applicationapparatus that does not provide this uniformity, since the spacingbetween adjacent ducts or plenum chambers is in effect wasted insofar asair application to roll surface is concerned.

Although I have described my improved uniform air application system inconnection with cylindrical rolls, it Will be apparent that the systemmay also be used in connection with surfaces of other shapes, such aswith flat surfaces. The air application system when used in connectionwith rolls for either heating or cooling the rolls may be used tocontrol the surface temperature profile across the rolls and thuscontrol the diameter profile of the rolls. Such control of diameterprofile is particularly important in connection with breaker stacks inwhich rolls that are unduly large in diameter in certain sectors alongtheir length will cause variation in thickness and other characteristicsacross the width of the paper passing through the breaker stacks. Myimproved air application system is not only useful with surfaces androlls of steel but is also useful in connection with surfaces and rollsof nylon or other material suitable for drying or breaker and calenderrolls, particularly for diameter control of the latter.

I wish it to be understood that the invention is not to be limited tothe specific constructions and arrangements shown and described, exceptonly insofar as the claims may be so limited, as it will be understoodto those skilled in the art that changes may be made without departingfrom the principles of the invention.

What is claimed is:

1. In mechanism for applying air on a roll, the combination of a hoodhaving a generally arcuate surface adapt-ed to extend around the roll atan approximately uniform distance therefrom, means defining a pluralityof plenum chambers in said hood extending longitudinally of the roll andincluding a wall for each chamber extending approximately parallel withthe roll surface and which walls collectively define said generallyarcuate surface, said walls each having a plane portion and two endzones extending at angles with respect to said plane portion, and meansfor applying air to said plenum chambers, said plane portions and saidend zones being provided with a plurality of openings extendingtransversely therethrough so spaced as to apply air jets at points whichare substantially uniformly spaced longitudinally of the roll and alsoarcuately of the roll substantially from one end of the hood to theother. i

2. A hoocl for applying air on a roll and having a ge1erally arcuatesurface to extend around the roll at an ap iroximately uniform distancetherefrom, said hood including means defining aplurality of airconducting plenum chambers in the hood Which extend longitudina'lly ofthe roll and which have walls" facing the roll and defining said arcuatesurface and also have side walls, said side Walls of adjacent ones ofsaid plenum chambers being substantially equally spaced and defining aireiihau's't passages therebetween, said roll facing Walls being providedwith rows of openings therethrou'gh extending longitudinally of the rolland including two side fows for each of said plenum chambers adjacentthe opposite sides of the plenum chamber and including also at least oneadditional intermediate row, each of said rows ineach of said rollfacing Walls being' spaced a predetermined distance apart ar'cuately ofthe roll and said plenum chambers being so closely disposed to eachother that the adjacent side rows of adjacent ones of said plenumchambers are also spaced substantially the same distance apart as therows in each of said roll facing walls and the openings in immediatelyadjacent ones of said longitudinal rows being staggered and so locatedwith respect to each other that the openings lie on lines extendinghelically around the roll so as to apply jets of air from said chamberson the surface of the roll which are substantially uniformly spaced bothlongitudinally of the roll and also arcuately of the roll.

References Cited in the file of this patent UNITED STATES PATENTS 1,488,953 Tensfeldt 6. Apr. 1, 192 4- 23 0 4, 818 Grupe Dec. 15, 19422,878,583 Spooner Mar. 24, 1959 2,919,495 Underhay Ian- 5,' 19602,928,135 Dreyv Mar. 15, 1960 3,012,335 Allander Dec. 12, 1961 FOREIGNPATENTS 727,058 Great Britain Mar. 30, 1955

2. A HOOD FOR APPLYING AIR ON A ROLL AND HAVING A GENERALLY ARCUATESURFACE TO EXTEND AROUND THE ROLL AT AN APPROXIMATELY UNIFORM DISTANCETHEREFROM, SAID HOOD INCLUDING MEANS DEFINING A PLURALITY OF AIRCONDUCTING PLENUM CHAMBER IN THE HOOD WHICH EXTEND LONGITUDINALLY OF THEROLL AND WHICH HAVE WALLS FACING THE ROLL AND DEFINING SAID ARCUATESURFACE AND ALSO HAVE SIDE WALLS, SAID SIDE WALLS OF ADJACENT ONES OFSAID PLENUM CHAMBERS BEING SUBSTANTIALLY EQUALLY SPACED AND DEFINING AIREXHAUST PASSAGES THEREBETWEEN, SAID ROLL FACING WALLS BEING PROVIDEDWITH ROWS OF OPENINGS THERETHROUGH EXTENDING LONGITUDINALLY OF THE ROLLAND INCLUDING TWO SIDE ROWS FOR EACH OF SAID PLENUM CHAMBER ADJACENT THEOPPOSITE SIDES OF THE PLENUM CHAMBER AND INCLUDING ALSO AT LEAST ONEADDITIONAL INTERMEDIATE ROW, EACH OF SAID ROWS IN EACH OF SAID ROLLFACING WALLS BEING SPACED A PREDETERMINED DISTANCE APART ARCUATELY OFTHE ROLL AND SAID PLENUM CHAMBERS BEING SO CLOSELY DISPOSED TO EACHOTHER THAT THE ADJACENT SIDE ROWS OF ADJACENT ONES OF SAID PLENUMCHAMBERS ARE ALSO SPACED SUBSTANTIALLY THE SAME DISTANCE APART AS THEROWS IN EACH OF SAID ROLL FACING WALLS AND THE OPENINGS IN IMMEDIATELYADJACENT ONES OF SAID LONGITUDINAL ROWS BEING STAGGERED AND SO LOCATEDWITH RESPECT TO EACH OTHER THAT THE OPENINGS LIE ON LINES EXTENDINGHELICALLY AROUND THE ROLL SO AS TO APPLY JETS OF AIR FROM SAID CHAMBERSON THE SURFACE OF THE ROLL WHICH ARE SUBSTANTIALLY UNIFORMLY SPACED BOTHLONGITUDINALLY OF THE ROLL AND ALSO ARCUATELY OF THE ROLL.